The present invention relates to a method and apparatus for determining or establishing alignment between a tool mounting assembly and a work surface of a machine tool and more particularly to such a method and apparatus for determining or establishing perpendicularity between a tool mounting assembly in the form of a rotatable chuck and a work surface of the machine tool.
In the operation of machine tools and the like, it is essential to assure initial alignment between a work surface of the machine tool and a tool mounting assembly or chuck for mounting a tool such as a drill or the like for engaging a work piece arranged upon the work surface.
During operation of such machine tools, it is commonly necessary to repeatedly reestablish proper alignment between the tool and the work surface. For example, substantial stresses may be developed during operation of the machine tool tending to create misalignment between the tool mounting assembly or chuck and the work surface. With the tool mounting assembly being a rotatable chuck, torque forces created by interaction of a rotating tool such as a drill with a workpiece arranged upon the work surface may tend to create misalignment between the chuck and the work surface.
In most instances, it is contemplated that the tool mounting assembly or chuck be exactly perpendicular with relation to the work surface. With such perpendicularity being established, any other desired angular relationship may then be achieved by proper adjustment between the tool mounting assembly or chuck and the work surface.
In the past, efforts to achieve such alignment with the work surface has involved the use of a leveling or alignment device of the type disclosed for example in U.S. Pat. No. 2,689,412 issued Sept. 21, 1954. The device of that patent includes means resting upon the work surface for establishing a predetermined angular relationship with the work surface. Such a device may of course not be satisfactory in assuring proper alignment of a tool secured in a tool mounting device or chuck.
A further example of prior art for assuring alignment between a tool mounting assembly or chuck and a work surface of such a machine tool is further disclosed in U.S. Pat. No. 3,763,570 issued Oct. 9, 1973. That patent includes a method and apparatus for achieving alignment or perpendicularity between a tool mounting assembly and a work surface by mounting separate leveling devices upon both the tool mounting assembly or chuck and the work surface. With a similar reading appearing upon each of the leveling devices, it may be assumed that the tool mounting assembly or chuck is in a desired alignment or is perpendicular to the work surface. However, such a device is depended upon skill of the operator in determining an exactly similar reading for each of the leveling devices. In addition, accuracy of the device of this patent is dependent upon similarity of the leveling devices themselves as well as their manner of attachment to the tool mounting assembly and the work surface.
Furthermore, devices such as that in the above noted patent are also dependent upon a stable environment for the machine tool to permit the obtaining of an accurate reading for the respective leveling devices. Accordingly, it may be difficult to properly align the components of the machine tool if the machine tool is not mounted upon a stable surface. For example, if the machine tool is to be operated on a ship or other unstable platform, the leveling devices of the above noted patent would be entirely unsatisfactory for achieving alignment within the machine tool.
Accordingly, there has been found to remain a need for a method and apparatus for determining or establishing alignment or perpendicularity between a tool mounting assembly such as a chuck and a work surface of a machine tool.